Recently, a semiconductor element is formed by laminating a plurality of wiring layers for downsizing it or high integration thereof. Further, a type of the semiconductor element is changed to a chip size package (CSP) or a wafer level package (WLP).
For these reasons, a case that a surface protective film and an interlayer insulating film are directly formed on a metal wiring (which is generally made of copper, copper alloy or the like) of the wiring layer is increased.
Therefore, adhesiveness between the films and the wiring made of copper, copper alloy or the like affects reliability of the semiconductor element remarkably. As a result, a film having high adhesiveness to the wiring made of copper, copper alloy or the like is required.
Further, from the viewpoint of a property and productivity of a package, it is required that the surface protective and interlayer insulating films (cured films) can be obtained through a curing treatment having a low curing temperature of 200 to 300° C., and have an excellent mechanical property such as elongation percentage.
In the case where the surface protective and interlayer insulating films can be obtained through the curing treatment having the low curing temperature, it is possible to prevent occurrence of damage due to heat in a high integration semiconductor element, and to improve productivity thereof.
For such a requirement, although there are known methods in which an additive ingredient is added to resin compositions for constituting the films in order to improve adhesiveness between the films and the copper and copper alloy (See, for example, Patent Document 1: Japanese Patent Application Laid-open No. 2005-336125 and Patent Document 2: Japanese Patent Application Laid-open No. 2005-173528), such methods could not improve the above adhesiveness sufficiently.
Further, for example, in the case of a package provided with an insulating film obtained by curing a conventional resin composition at a low curing temperature, when solder balls were mounted onto the package, there was a case that appearance abnormalities such as rucks and cracks occurred on a surface of the insulating film due to a treatment using a flux or the like.